Most kelp (Saccharina latissima) farms in the Gulf of Maine reside in coastal, sheltered areas and are ephemeral, being fully deployed and removed every growing season. We assess whether the deployment of gear and growth of biomass at these farm sites provide seasonal habitat used by other organisms. Habitat, and the biodiversity of other species associating with farms, is considered a type of “supporting” ecosystem service. Ecosystem services are the benefits humans receive from healthy ecosystems. Of all ecosystem service categories – supporting, provisioning, regulating, and cultural, – supporting services are the least studied for temperate seaweed aquaculture. Quantifying biodiversity to understand the ecosystem that regenerative aquaculture creates, will promote climate resilience and sustainable industry growth.
We quantified mobile vertebrates (fish, seals) and crustaceans (crabs, lobsters) interacting with kelp farms using GoPro cameras. We also assessed small (< 5mm) invertebrates using mesh settling devices suspended at the same depth as kelp lines (2m). Both fish and invertebrate visual surveys were paired with environmental DNA (eDNA) methods. Alpha and beta diversity results suggest that kelp farm habitat has no impact on the richness, biodiversity, or types of species in this region. However, differences in alpha diversity measurements were seen between seasons, with higher species richness and Shannon Weiner diversity indices during the summer non-growing season when compared to the winter growing season. Differences in the types of species present were also occurring between the two seasons. Specifically, American lobsters were driving this significant difference with a higher abundance of lobsters present during the summer non-growing season. Other studies reveal seaweed farm habitat values vary based on a range of factors including: species cultivated, local environmental characteristics, farm management practices, etc. In the Gulf of Maine, a large percent of the species assemblage migrates offshore during the winter growing-season, resulting in little habitat needed near shore.